Method of manufacturing copperlead alloy coated graphite powder



Patented July 13, 1954 METHOD OF MANUFACTURING COPPER- LEAD ALLOY COATED GRAPHITE POWDER Tatsuo Matsukawa, Asahiku, Osaka, Japan No Drawing. Application March 4, 1952,

Serial No. 274,823

2 Claims.

This invention relates to the method of manufacturing copper-lead alloy coated graphite powder which is prepared by agitating the mixture of powder of zinc base alloy containing lead and that of graphite in the aqueous solution of copper salt added to them, and which is applied to materials suitable for the sintered alloy used as metal-graphite electrical brush, self-lubricating bearing metal and pantograph slider.

Materials used in the sliding part such as those above mentioned are usually manufactured by sintering copper and graphite powder, and especially, in addition to those, lead powder to reduce frictional affect. But, since'these powders differ in their form and specific gravity in dividually, it is so difiicult to mix them uniformly that a special technique is required to obtain the uniform product.

The following technique to distribute copper and graphite uniformly has been invented by the author and is described in detail in the specifications of Japanese Patents Nos. 175,387, 176,971 and 184,994. That is to coat graphite powder with copper by agitating the mixture of powder of zinc, iron or copper-zinc alloy (0.5-2.5 copper and zinc as balance), and that of graphite in the aqueous solution of copper sulphate or copper chloride poured onto them.

This invention proves, after the later research, that the graphite powder is able to be coated with copper-lead alloy by washing and drying the product which is obtained by agitating the mixture of powder of zinc base alloy including lead and that of graphite in the aqueous solution of copper salt added to them.

In this invention, the powder of zinc base alloy including lead, above mentioned, means as follows:

(1) Copper-lead-zinc alloy powder (in which lead is -10%, copper 05-20% and zinc as balance).

(2) Lead zinc alloy powder (lead 05-10% and zinc for the rest).

A grain size of 80-200 mesh grade is considered suitable.

With regard to the aqueous solution of copper salt, that of copper sulphate or copper chloride is preferred, but that of copper acetate or other copper salt is also available.

When the aqueous solution of copper salt is added to the mixture of powder of zinc base alloy containing lead and that of graphite, the alloy powder forms a galvanic cell with the graphite powder owing to dissolution of zinc. And the copper in the solution is deposited on the surface of cathodic powder of graphite.

Some of the fine powder of lead, resulting from decomposition of the alloy powder, is em- Metal graphite electrical brush, self-lubricating bearing metal or pantograph slider, manufactured by' means of powder metallurgy using the kind of coated powder above described, have excellent characteristics with smaller values in their coefficients of friction and less obliteration.

A few examples in practical application of this invention are as follows:

Example 1 1,040 cc. of aqueous solution of copper sulphate (containing 0.05 g. of copper in 1 cc. of the solution) is poured into a mixture of g. of copperlead-zinc alloy powder (the composition is 15% copper, 5% lead and zinc, and the grade of powder is below 120 mesh) and 35 g. of graphite powder (below 150 mesh grade), and stirred up. After the depositing reaction of copper is over, the product is washed and dried.

Example 2 1,384 cc. of aqueous solution of copper sulphate (containing 0.05 g. of copper in 1 cc. of the solution) is added to a mixture of '75 g. of lead-zinc alloy powder (consists of 5% lead and zinc, and the size of powder is below mesh grade) and 25 g. of graphite powder (below mesh grade), and stirred up. After the depositing reaction of copper is concluded, the powder is washed and dried.

To illustrate the distributed state of lead for each size of powder in this method, the relation between grade distribution of raw graphite powder applied in the first example and that of produced powder of graphite coated with copperlead alloy, and as well the contents of lead and graphite in the latter, are shown in the following table.

Size of powder. in mesh 150-200 the product, in percent 30. 7

2,ees,ese

The tab shows that the product is larger in size than the raw graphite powder due to the coating oi. copper-lead alloy, and the contents or lead in every grade of powder is nearly equal. It proves that the graphite powder is 5 able to be coated with copper-lead alloy of uniform structure by this method invented by the author. I

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than bythe terms of the appended claims.

Having now described my invention, what I claimasnewand desiretosecurebyLettersPatent is:

l. A process of coating graphite powder with a copper-lead alloy which comprises agitating in an aqueous solution of a copper salt the graphite 20 vChemical. Abstracts, vol. 45, No. 19 (Oct. 20,

powder in admixture with a lead-zinc alloy powder consisting of 0.5 to 10% lead, and the remainder sine.

. 4 2. A process of coating graphite powder with a copper-lead alloy which comprises agitating in an aqueous solution of a copper salt the graphite powder in admixture with a lead-zinccopper alloy powder consisting of 0.5 to 10% lead. 0.5 to 20% copper, and the remainder zinc.

' References Cited in the flle of this patent 10 UNITED s'rs'ms PATENTS Number I Name Date Re. 5.044 Knight Aug. 27, 1872 20,353 Knight May 25, 1858 901,905 Harrison Oct. 2?, 1908 is 901,966 Harrison Oct. 27, 1908 1,582,617 uolin Apr. 27, 1920 2,414,514 Else Jan. 21, 1947 OI'HIBREFERENCEB 

1. A PROCESS OF COATING GRAPHITE POWDER WITH A COOPER-LEAD ALLOY WHICH COMPRISES AGITATING IN AN AQUEOUS SOLUTION OF A COPPER SALT THE GRAPHITE POWDER IN ADMIXTURE WITH A LEAD-ZINC ALLOY POWDER CONSISTING OF 0.5 TO 10% LEAD, AND THE REMAINDER ZINC. 